Cancer genetics and diagnosis
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This document discusses cancer genetics and diagnosis. It begins by defining cancer and tumors, explaining that cancer is characterized by uncontrolled cell growth that causes malignant tumors. It then explains that cancer arises from mutations in DNA, particularly in cancer genes like tumor suppressor genes and oncogenes. Tumor suppressor genes normally prevent cell growth but mutations cause loss of function, while oncogenes promote cell growth but mutations result in constant activity. Some cancers are caused by viruses like HPV. Cancer diagnosis is usually based on finding lumps or masses, not genetics. Treatments include surgery, radiation, chemotherapy, anti-angiogenesis drugs, and differentiation therapies.
Cancer genetics and diagnosis
- 1. Cancer Genetics and Diagnosis Kishan Sharma M.Sc. 2nd Year Biotechnology Manipal University Jaipur
- 2. Cancer Disease characterized by uncontrolled cell growth. This causes tumors. Tumors may be benign or malignant. Benign tumors grow in size but do not invade and destroy surrounding tissue. Cancer usually means malignant. Malignancy means a cell is invasive. Invasion destroys The internal cellular order of a tissue. Membranes and barriers that define organs.
- 3. Cancer All cancers derive from single cells that have acquired the characteristics of continually dividing in an unrestrained manner and invading surrounding tissues. Cancer cells behave in this abnormal manner because of changes in the DNA sequence of genes, which are known as cancer genes.
- 4. Mutation • Germline mutation – A change in the DNA sequence that can be inherited from either parent. • Somatic mutation – A change in the DNA sequence in cells other than sperm or egg. – The mutation is present in the cancer cell and its offspring, but not in the patient’s healthy cells.
- 5. Mutations & cancer genes Mutations in cancer genes can occur somatically or can be inherited. Mutations in some cancer genes can be inherited from parents, in which case they are present in every cell of the body. Such people are at a higher risk of developing cancer. Somatic mutations can occur in any of the cells of the body except the germ cells (sperm and egg) and therefore are not passed on to children.
- 6. Cancer genes There are two types of cancer genes: Tumor suppressor genes Oncogenes
- 7. Cancer genes Tumor suppressor genes : These genes normally function to prevent cell growth/division. They can halt the cell growth cycle to stop unnecessary division or promote cell death if the cell’s DNA is damaged. When this gene mutates to cause a loss in its function, the cell can progress to cancer, usually in combination with other genetic changes. Retinoblastoma (cancer of retina) caused by losing function of RB gene.
- 8. Cancer genes Oncogenes: Genes which normally function to promote cell growth/division in a controlled manner. Proto-oncogenes code for proteins that drive cell division. When these genes acquire mutations that result in continually active proteins they become oncogenes and cause uncontrolled cell growth and division.
- 9. Viruses Are Associated with Some Cancers Viruses are responsible for a number of cancers in animals, humans. For example, about 95% of all women with cervical cancer are infected with human papilloma viruses (HPVs). Human papilloma virus causes benign tumors of epithelial cells. 70% of the cases of cervical cancer are caused by HPV-16 and HPV-18.
- 10. Colorectal Cancer Arises Through the Sequential Mutation of a Number of Genes
- 11. Hereditary Breast/Ovarian Cancer BRCA1 and BRCA2 genes. Associated with defective DNA repair complex that repairs breaks and cross-links in DNA.
- 12. Cancer Diagnosis Because cancer is caused by many different genes diagnosis is not genetic. Usually diagnosed after finding a lump ,either feeling it or visualizing it on MRI. Labelled by tissue where cancer begin.
- 13. Cancer Treatments Surgery – Removal of tumor and removal of susceptible tissue. Radiation and Chemotherapy – Kill off cells that are rapidly dividing. Treat specific form of cancer present. Prevent angiogenesis: –Stop tumor from vascular growth, however, stops all vascular growth. Promote cells to differentiate: –try to coax cells back to original cell type.
- 14. Thank You
Editor's Notes
- #3: Laryngeal papillomas for example can occlude the airway and cause asphyxiation
- #7: e.g.-
- #8: Rb's normal function: –Halt mitosis to give time for DNA repair before division p53 –transcription factor that sends the cell into apoptosis Loss of p53 function –no apoptosis
- #9: Ras gene – identified from cancer causing viruses, first derived from Rats AND s means Sarcoma, discovered in human cancer cells Ras gene products are involved in signalling pathways that help control transcription of genes that are involved in cell growth and differentiation.
- #10: These viruses cause cervical cancer by producing a protein that attaches and inactivates RB and p53, two proteins that play key roles in the regulation of the cell cycle. When these proteins are inactivated, cells are stimulated to progress through the cell cycle and divide without the normal controls that prevent cell proliferation. (uterus)
- #11: APC gene – Adenomatous polyposis coli Ras gene – identified from cancer causing viruses, first derived from Rats AND s means Sarcoma, discovered in human cancer cells P53 gene - About 75% of colorectal cancers have mutations in tumor-suppressor gene p53. Because p53 prevents the replication of cells with genetic damage and controls proper chromosome segregation, mutations in p53 may allow a cell to rapidly acquire further gene and chromosome mutations, which then contribute to further proliferation and invasion into surrounding tissues. FAP –familial colon cancer •Family members inherit mutation in APC gene in Mendelian fashion •Family members have small benign polyps in their colon even as young children •APC gene normally regulates mitosis •Lose second allele of APC –grow polyp •Polyp selects for further mutations •Further mutations become cancer
- #12: These are tumor suppressor genes
- #13: MRI – Magnetic Resonance Imaging
- #14: Specific Treatments •Use phenotype to determine drug: –Breast cancer with estrogen receptors –block estrogen •Use genotype to determine drug: –BRCA1 and Her-2/neu genotypes determine next step Her-2/neu protein is a receptor for a growth factor –a proto-oncogene •Cancer cells genotyped •If Her-2/neu positive •Treat with Herceptin –an antibody that binds to Her-2/neu receptors •Therefore blocks their signal to divide •Cancer cells gain cell cycle control once again